There are different types of avalanches depending on the snow they are formed from, the way they fall etc. Avalanches can be wet, dry, hard and soft. The most dangerous are the slab avalanches since they are very destructive. Which factors can contribute to producing an avalanche? These are the weather, the snowfall and the terrain. Avalanches may occur after or during a storm or when the temperature suddenly rises or there is a heavy thaw. The wind direction is important as well. A significant snowfall also has to be taken into account.

Usually avalanches occur on slopes between 25 and 45 degrees facing east, north and northeast but they can occur on any other slopes also depending on conditions. Convex slopes are considered to be more dangerous. You should avoid traveling below cornices. Probably one of the most important factors is the condition of the snow pack. That is why the snow pack condition should be checked for layers of loose grains or ice, soft layers, layers of graupel, airspace, weak layers deep in the snow pack, grainy snow crystals etc. The observation of the snow pack is absolutely necessary. A snow pit will show you what is the structure of the snow pack i.e. the layers of the snow and are there any weak layers. A snow pit can be dug with a shovel. It will be nice to dig a pit 1-1,5 m high and about 1m deep. You can feel the hardness of a layer with your hand and see whether you are going to find any weak layer. You have to look for the following signs:

- Layer of loose grains;
- layer of ice;
- layer of graupel;
- very soft layer (if there is a very soft layer on a hard layer or relatively hard layer on a very soft layer);
- rain drops (they can weaken the bonds between the layers of snow);
- airspace;

Avalanche can occur in the following conditions:
- the old snow layer is higher than 30-50 cm;
- the new snow layer is 25-30cm;
- the intensity of a snowfall has to be determined by the quantity of snow fallen for a period of time (per time unit). If the snowfall is about 50 cm within 10-12 hours, it can cause an avalanche;
- Wind speed of 7-8 m per second;
- Air temperature (especially in spring when the surface layers of the snow start melting and water drops fall down this way weakening the snow pack);
- Animals, people, gunshots, rock or ice fall and heavy sounds can cause an avalanche as well.

Since to avoid avalanche is much easier than to survive an avalanche, the best thing, of course, is to avoid avalanche terrains, especially the steep slopes. You should always carry proper equipment. Always observe the terrain and the condition of the snow and snow pack. Perform tests - it doesn't take long. Take into consideration the weather conditions and make your own evaluation.

Iavor Angelov is a webmaster, content writer http://www.aiai-net.org/ and programmer.